1. Field of the Invention
The present invention relates to a semiconductor manufacturing apparatus and a method of manufacturing a semiconductor device and, more particularly, to a technique for forming a lead of a semiconductor device.
2. Description of the Background Art
Background art first and second lead forming apparatuses 100P and 200P will be described hereinafter with reference to FIGS. 13 through 17.
First, a semiconductor device 10P is prepared which has leads 11P projecting from a package 12P in first and third directions D1 and D3 (both horizontal) perpendicular to each other. Only leads 11P projecting in the first direction D1 are shown in FIGS. 13 through 16, and the forming of these leads 11P will be mainly described. The semiconductor device 10P is placed on a die 151P fixed to a lower body of a press (not shown) of the first lead forming apparatus 100P.
An upper body of the press including a punch holder 110P, an openable block 120P, a stripper 181P and the like moves downwardly in a second direction D2 (vertical). At the start of the downward movement, the stripper 181P and the die 151P together hold therebetween part of the lead 11P which is near the package 12P. As the upper body continues moving downwardly, an end portion 101T1P of a punch 101P comes into contact with the lead 11P.
A structure of the upper body will be described below. The punch 101P is mounted on the punch holder 110P for pivotal movement about a shaft 105P both in a direction indicated by the arrow A11P (also referred to hereinafter as an xe2x80x9copening direction A11Pxe2x80x9d) and in a direction indicated by the arrow A12P (also referred to hereinafter as a xe2x80x9cclosing direction A12Pxe2x80x9d). An end portion 101T2P of the punch 101P opposite from the end portion 101T1P with respect to the shaft 105P and the punch holder 110P are coupled to each other by a spring 106P. The spring 106P urges, or exerts a pivoting force on, the end portion 101T2P in the opening direction A11P. A roller 101RP is mounted on the end portion 101T2P and is in contact with a vertical surface 120S1P or an inclined surface 120S2P of the openable block 120P. The openable block 120P and the punch holder 110P are movable in the second direction D2 independently of each other. At the start of the downward movement of the upper body, the roller 101RP is in contact with the vertical surface 120S1P, and the end portion 101T1P is at the limit of the pivotal movement of the punch 101P in the opening direction A11P. Although only the single punch 101P and the components associated with the operation thereof are shown in FIGS. 13 through 16 for purposes of illustration, the background art lead forming apparatus 100P comprises a plurality of such structures. For example, for the package 12P (known as a QFP (Quad Flat Package)) of a quadrilateral configuration as viewed in the second direction D2 with the leads 11P projecting from the four end surfaces 12SP (as shown in FIG. 17) of the package 12P which correspond, respectively, to the four sides of the quadrilateral configuration, the punch 101P and its associated components are provided for each of the end surfaces 12SP. This holds true for the second lead forming apparatus 200P to be described later.
The upper body stops moving downwardly when the end portion 101T1P comes into contact with the lead 11P. Thereafter, the openable block 120P moves upwardly. As the openable block 120P moves upwardly, the roller 101RP moves along the inclined surface 120S2P, and the end portion 101T1P accordingly pivots about the shaft 105P in the closing direction A12P. Such a pivotal movement causes the lead 11P to be bent in a direction indicated by the arrow A1P of FIG. 13. Specifically, the pivotal movement of the end portion 101T1P in contact with the lead 11P in the closing direction A12P forces a punch-side forming surface 101SP (shown in FIG. 14) to bend the lead 11P toward a die-side forming surface 151SP (shown in FIG. 14).
When the lead 11P is bent into a predetermined configuration, the openable block 120P stops and then starts moving downwardly. This causes the end portion 101T1P to pivot in the opening direction A11P to bring the punch 101P out of contact with the lead 11P. Thereafter, the upper body and the stripper 181P move upwardly, and the upper body returns to its original position. This completes a series of operations.
After the first lead forming apparatus 100P forms a shoulder of the lead 11P, the second lead forming apparatus 200P forms a distal portion of the lead 11P. This forms the lead 11P into a final configuration.
As illustrated in FIGS. 15 and 16, the second lead forming apparatus 200P is similar in construction to the first lead forming apparatus 100P except that a die-side forming surface 252SP of a die 252P and a punch-side forming surface 201SP of a punch 201P differ in configuration from the above described forming surfaces 151SP and 101SP (shown in FIG. 14). The forming surfaces 252SP and 201SP of the second lead forming apparatus 200P are configured and sized to conform to the final configuration of the lead.
The second lead forming apparatus 200P performs an operation similar to that of the first lead forming apparatus 100P described above to finish the semiconductor device 10P having the leads 11P shown in FIG. 17.
The background art lead forming apparatuses 100P and 200P present problems to be described below. Although the problems with the first lead forming apparatus 100P are described below, the description applies equally to the second lead forming apparatus 200P.
 less than Problem (1): Scratch on Lead Being Formed greater than 
As above described, the background art lead forming apparatus 100P bends the lead 11P by pivoting the end portion 101T1P in contact with the lead 11P in the closing direction A12P. Since the end portion 101T1P moves or lowers in the second direction D2 while being pivoted during the bending, i.e., slides on the lead 11P, the lead 11P is scratched or a metal plating is removed from the lead 11P. It is contemplated that the background art lead forming apparatus 100P can alleviate the sliding movement to some extent by rendering the punch 101P pivotable about the shaft 105P. In the lead forming apparatus 100P, however, the center of curvature of the lead 11P being bent does not always coincide with the center (of curvature) of a path of movement of the end portion 101T1P. In other words, the shape of the lead 11P being bent is not taken into consideration to pivot the end portion 101T1P. This might causes an intensive pressure to be applied between the end portion 101T1P and the lead 11P. It is therefore difficult to completely prevent the above described scratches and the like.
Additionally, the lead 11P held between the stripper 181P and the die 151P might be dented. When a force that lifts the semiconductor device 10P is developed by the above described sliding movement and exerted upon the lead 11P, such a dent is significantly great.
The scratches and the like on the lead 11P give rise to the oxidation or corrosion of the lead 11P to result in the increase in resistance of the lead 11P or a break in the lead 11P, causing the semiconductor device 10P to be incapable of performing a predetermined operation.
 less than Problem (2): Nonuniform Lead Configurations greater than 
As above described, the background art lead forming apparatus 100P comprises the punch 101P and its associated components which are provided for each end surface 12SP of the package 12P. Thus, variations in size of the punch 101P and the die 151P occur due to, for example, manufacturing accuracy and wear with time to cause differences in clearance between the punch 101P and the die 151P. In view of the fact that the punches 101P are similarly disposed in a predetermined position of the upper body, the bending of the leads 11P with the differences in clearance maintained gives rise to variations in timing of contact between the punch 101P and the lead 11P. In such a case, it is difficult to impose a uniform forming load on all of the leads 11P. Therefore, variations in configuration of the leads 11P occur throughout the semiconductor device 10P.
Another background art technique is such that a plurality of semiconductor devices 10P are arranged, for example, linearly on the die 151P and the single punch 101P simultaneously bends all of the leads 11P arranged in the direction in which the semiconductor devices 10P are arranged. In this operation, a forming load from the press is imposed simultaneously on the multiplicity of leads 11P. However, uniformly placing the forming load sufficient for the bending upon the leads 11P is difficult because of the very large number of leads 11P. Thus, application of such a forming technique also presents the problem of variations in lead configuration.
Further, the stripper 181P and the die 151P hold the plurality of leads 11P therebetween. When, for example, warpage or disorder exists in the array of leads 11P (at their proximal ends) projecting from the same end surface 12SP, the leads 11P are held with the warpage or disorder corrected. After the leads 11P are formed under such a situation, the warpage or disorder is restored by the release of the corrective force. As a result, the array or arrangement of distal portions of the formed leads 11P reflects the warpage or disorder.
The semiconductor device 10P thus manufactured comprises the leads 11P having the respective distal portions which do not lie in the same plane because of the nonuniformity of the leads 11P. Hence, the semiconductor devices 10P manufactured by the background art lead forming apparatus 100P do not provide a sufficient bonding strength when mounted and soldered onto a circuit board.
According to a first aspect of the present invention, a semiconductor manufacturing apparatus comprises: a die having a die-side forming surface of a predetermined configuration and capable of receiving a semiconductor device including a package and a lead projecting from the package, with the lead in face-to-face relationship with the die-side forming surface; a punch having an end portion provided with a punch-side forming surface in face-to-face relationship with the die-side forming surface, the end portion performing a predetermined working operation upon the lead; and a driver for moving the end portion of the punch substantially squarely toward the die-side forming surface, with the punch-side forming surface and the die-side forming surface maintained in parallel relationship.
Preferably, according to a second aspect of the present invention, the semiconductor manufacturing apparatus of the first aspect further comprises: a pressure detector for detecting a load placed upon the end portion; and a controller for controlling the driver based on the load detected by the pressure detector.
Preferably, according to a third aspect of the present invention, the semiconductor manufacturing apparatus of the first or second aspect further comprises a resilient element between the end portion and the driver.
Preferably, according to a fourth aspect of the present invention, the semiconductor manufacturing apparatus of any one of the first to third aspects further comprises a rotative driver for rotating at least one of the punch, the die and the semiconductor device about the package, with a positional relationship maintained between the punch, the die and the semiconductor device relative to each other.
Preferably, according to a fifth aspect of the present invention, the semiconductor manufacturing apparatus of any one of the first to fourth aspects further comprises a retainer having a mechanism for adhering to the package under suction, the retainer coming into contact with the package on an opposite side from the die to hold the semiconductor device.
Preferably, according to a sixth aspect of the present invention, the semiconductor manufacturing apparatus of any one of the first to fifth aspects further comprises a contact detector for detecting contact between the end portion and the die-side forming surface, with the lead therebetween.
Preferably, according to a seventh aspect of the present invention, in the semiconductor manufacturing apparatus of any one of the first to sixth aspects, the lead of the semiconductor device includes a plurality of leads; and the punch performs the predetermined working operation simultaneously upon a group of leads projecting substantially in the same direction among the plurality of leads.
Preferably, according to an eighth aspect of the present invention, in the semiconductor manufacturing apparatus of the seventh aspect, the group of leads are divided into at least two blocks; and adjacent ones of the leads included in each of the blocks are connected at their tips to each other.
Preferably, according to a ninth aspect of the present invention, in the semiconductor manufacturing apparatus of any one of the first to eighth aspects, the punch includes a plurality of punches movable independently of each other.
Preferably, according to a tenth aspect of the present invention, in the semiconductor manufacturing apparatus of the ninth aspect, the end portion of each of the punches is capable of independently placing a predetermined forming load upon the lead.
According to an eleventh aspect of the present invention, a method of manufacturing a semiconductor device comprises the steps of: placing a semiconductor device including a package and a lead projecting from the package on a die having a die-side forming surface of a predetermined configuration, with the lead in face-to-face relationship with the die-side forming surface; and bringing an end portion of a punch having a punch-side forming surface in face-to-face relationship with the die-side forming surface into contact with an opposite side of the lead from the die-side forming surface and moving the end portion of the punch substantially squarely toward the die-side forming surface, with the punch-side forming surface and the die-side forming surface maintained in parallel relationship.
Preferably, according to a twelfth aspect of the present invention, in the method of the eleventh aspect, the punch-side forming surface and the die-side forming surface hold the lead therebetween, with a predetermined forming load placed on the lead.
In accordance with the first aspect of the present invention, the end portion of the punch is moved substantially squarely toward the die-side forming surface to bend the lead. Thus, the apparatus of the first aspect of the present invention can reduce the sliding movement of the end portion on the lead, as compared with the background art semiconductor manufacturing apparatus. Thus, the apparatus of the first aspect can significantly reduce scratches on and metal plating removal from the lead resulting from the sliding movement, to consequently manufacture the semiconductor device which is free from troubles resulting from the lead scratches and the like and reliably exhibits its predetermined characteristic.
Additionally, the apparatus of the first aspect which thus reduces the sliding movement of the end portion on the lead requires a much smaller force developed by the sliding movement during the lead forming operation and operable to lift the semiconductor device than do the background art semiconductor manufacturing apparatus. As a result, the need to rigidly hold the lead between the stripper and the die of the background art semiconductor manufacturing apparatus to retain the semiconductor device on the die is eliminated.
In accordance with the second aspect of the present invention, the pressure detector and the controller can accurately control the load when the end portion and the die-side forming surface hold the lead therebetween. Thus, the apparatus of the second aspect can reliably place a predetermined forming load upon the lead held between the end portion and the die-side forming surface, to therefore form the lead of a predetermined configuration reliably and accurately.
In accordance with the third aspect of the present invention, when the end portion which is controlled based on only a relative amount of movement to move is deviated from its proper position, the apparatus of the third aspect can accommodate the deviation. In other words, the apparatus of the third aspect provides allowance in the action of the end portion coming into contact with the lead to place the above-mentioned predetermined forming load thereon. This alleviates the abrupt movement of the end portion resulting from the above-mentioned deviation. Therefore, the apparatus of the third aspect prevents damages to the lead due to the abrupt movement when the deviation occurs. Further, the resilient element accommodate s the above-mentioned deviation to ensure the loading operation.
In accordance with the fourth aspect of the present invention, when the semiconductor device has a plurality of leads projecting in different directions, the rotation of at least one of the punch, the die and the semiconductor device allows, for example, the single punch to form the leads. Therefore, the semiconductor manufacturing apparatus is provided at low costs.
The provision of punches for the respective directions in which the leads project requires a high accuracy of positioning of the punches in some cases. However, the smaller number of punches of the apparatus of the fourth aspect alleviates the positioning accuracy.
Further, when the semiconductor manufacturing apparatus comprises, for example, the single punch, the apparatus of the fourth aspect can flexibly meet the requirement of the manufacture of various types of semiconductor devices differing in size of the package or in the number of leads. Thus, the semiconductor manufacturing apparatus of the fourth aspect is very high in practicality and general versatility.
In accordance with the fifth aspect of the present invention, the retainer can adhere to the package under suction to reliably hold the semiconductor device. At this time, the apparatus of the fifth aspect does not hold the lead between the stripper and the die as has been done by the background art apparatus. Hence, the lead is not dented. Therefore, the apparatus of the fifth aspect can manufacture the semiconductor device which is free from troubles resulting from the dents on the lead and reliably exhibits its predetermined characteristic. Additionally, the apparatus of the fifth aspect, unlike the background art semiconductor manufacturing apparatus, need not correct the warpage and the like of the leads to perform the predetermined working operation since the retainer does not hold the lead on opposite side thereof. Thus, the apparatus of the fifth aspect can form the leads of the predetermined configuration reliably and accurately without being affected by the warpage, if any, in the leads.
Additionally, the rotative driver of the fourth aspect may be used to rotate the retainer, eliminating the need to remove the semiconductor device externally of the die to rotate the semiconductor device. This does not require the time to remove the semiconductor device externally of the die to shorten the manufacturing time.
In accordance with the sixth aspect of the present invention, contact is detected between the end portion of the punch and the die-side forming surface. When the end portion which is controlled based on only a relative amount of movement to move is deviated from its proper position before contacting the die-side forming surface, the apparatus of the sixth aspect can correct the positions of the end portion and the die-side forming surface relative to each other or the clearance therebetween when in contact. The contact detector may be also used to specify a contact home position between the punch-side forming surface and the die-side forming surface for pre-operation adjustment (without placing the semiconductor device in position). Thus, the use of the contact detector provides a precise predetermined clearance before and/or during the lead forming operation. Therefore, the apparatus of the sixth aspect can perform the predetermined working operation on the lead with accuracy, to consequently form the lead of the predetermined configuration reliably and accurately.
In accordance with the seventh aspect of the present invention, any one of the above described effects of the first to sixth aspects may be produced when the single punch is used to form the group of leads simultaneously. In particular, the apparatus of the seventh aspect can form the group of leads having uniform quality, that is, allows the distal portions of all of the leads to lie in the same plane when the semiconductor device is mounted on a circuit board. Therefore, the apparatus of the seventh aspect can manufacture the semiconductor device solderable with a sufficient bonding strength.
In accordance with the eighth aspect of the present invention, the apparatus can suppress or prevents forming troubles such as a lead skew and a twisted lead. Further, the apparatus of the eighth aspect is effective in that the leads are more difficult to reflect the deformation of the package than the leads all of which are connected together in the group. Therefore, the apparatus of the eight aspect can form the leads having the predetermined configuration reliably and accurately.
In accordance with the ninth aspect of the present invention, the plurality of punches are movable independently of each other to accommodate a difference in clearance between the punches and the dies resulting from, e.g., the dimensional accuracy thereof. Each of the punches can suitably perform the predetermined working operation. Hence, when the semiconductor device has, for example, a plurality of lead groups and the punch is provided for each of the lead groups, the apparatus of the ninth aspect eliminates variations in the configuration of the formed leads included in each lead group. Therefore, the leads having the predetermined configuration may be formed reliably and accurately throughout the semiconductor device.
In accordance with the tenth aspect of the present invention, the end portion of each of the punches is capable of independently placing the predetermined forming load upon the lead. This prevents the forming load from being affected by, e.g., the dimensional accuracy of the punch and the die or the number of leads formed by the single punch, unlike the background art semiconductor manufacturing apparatus. Therefore, the apparatus of the tenth aspect can place the predetermined forming load, i.e., a more sufficient load upon the lead than can the background art apparatus, to form the lead having the predetermined configuration reliably and accurately.
In accordance with the eleventh aspect of the present invention, the end portion of the punch is moved substantially squarely toward the die-side forming surface to bend the lead. Thus, the method of the eleventh aspect can reduce the sliding movement of the end portion on the lead, as compared with the background art method. Thus, the method of the eleventh aspect can significantly reduce scratches on and metal plating removal from the lead resulting from the sliding movement, to consequently manufacture the semiconductor device which is free from troubles resulting from the lead scratches and the like and reliably exhibits its predetermined characteristic.
In accordance with the twelfth aspect of the present invention, the lead is held on opposite sides with the predetermined forming load placed thereon without being affected by, e.g., the dimensional accuracy of the punch and the die or the number of leads formed by the single punch. Therefore, the method of the twelfth aspect can place a more sufficient load upon the lead than can the background art method, to form the lead having the predetermined configuration reliably and accurately.
It is therefore a primary object of the present invention to provide a semiconductor manufacturing apparatus and a method of manufacturing a semiconductor device which can significantly reduce scratches on and metal plating removal from a lead being formed, as compared with conventional semiconductor manufacturing apparatuses.
It is another object of the present invention to provide a semiconductor manufacturing apparatus and a method of manufacturing a semiconductor device which can form a lead of a predetermined configuration reliably and accurately.
It is still another object of the present invention to provide a highly practical, highly versatile and less expensive semiconductor manufacturing apparatus to accomplish the above described objects.
It is a further object of the present invention to provide a semiconductor manufacturing apparatus for manufacturing a semiconductor device solderable with a sufficient bonding strength.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.